title: Structure and dynamics of spin-labeled insulin entrapped in a silica matrix by the sol-gel method.
abstract: The structure and conformational dynamics of insulin entrapped into a silica matrix was monitored during the sol to maturated-gel transition by electron paramagnetic resonance (EPR) spectroscopy. Insulin was successfully spin-labeled with iodoacetamide and the bifunctional nitroxide reagent HO-1944. Room temperature continuous wave (cw) EPR spectra of insulin were recorded to assess the mobility of the attached spin labels. Insulin conformation and its distribution within the silica matrix were studied using double electron-electron resonance (DEER) and low-temperature cw-EPR. A porous oxide matrix seems to form around insulin molecules with pore diameters in the order of a few nanometers. Secondary structure of the encapsulated insulin investigated by Fourier transform infrared spectroscopy proved a high structural integrity of insulin even in the dried silica matrix. The results show that silica encapsulation can be used as a powerful tool to effectively isolate and functionally preserve biomolecules during preparation, storage, and release.
authors.affiliation: Faculty of Physics & Institute of Interdisciplinary Research in Bio-Nano-Sciences, Babes-Bolyai University, Cluj-Napoca, Romania.
authors.forename: E
authors.initials: E
authors.lastname: Vanea
authors.forename: C
authors.initials: C
authors.lastname: Gruian
authors.forename: C
authors.initials: C
authors.lastname: Rickert
authors.forename: H-J
authors.initials: HJ
authors.lastname: Steinhoff
authors.forename: V
authors.initials: V
authors.lastname: Simon
mesh_terms: D000818:Animals; D002417:Cattle; D004337:Drug Carriers / Q000737:chemistry*; D004339:Drug Compounding; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D007004:Hypoglycemic Agents / Q000737:chemistry*; D007328:Insulin / Q000737:chemistry*; D008958:Models, Molecular; D053758:Nanoparticles / Q000737:chemistry; D010316:Particle Size; D044367:Phase Transition; D016062:Porosity; D017433:Protein Structure, Secondary; D058428:Silica Gel / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013113:Spin Labels
chemical_list: D004337:Drug Carriers; D007004:Hypoglycemic Agents; D007328:Insulin; D013113:Spin Labels; D058428:Silica Gel